Circuit control system

ABSTRACT

A remotely controlled circuit control device has first and second load contact assemblies movable into circuit engagement and circuit disengagement positions relative to one another in which one load contact assembly is operatively connected to a solenoid so that alternate forward strokes of the solenoid moves the one load contact assembly between reset and tripped positions through a push-push mechanism having an indexing portion and a latching portion. An overload mechanism cooperates with the latch portion to cause the load contact assemblies to move to the circuit disengaged position upon occurrence of a fault condition. The second load contact assembly includes pivotably mounted contact members which are linked to the first load contact assembly in such a way that circuit engagement during solenoid energization is precluded. The push-push mechanism is operatively connected via a mode switch to either a reset circuit or a trip circuit and in turn to a remotely disposed indicator-control unit (ICU) through an optical coupler. Contact status and coordination between load contacts and ICU contacts are provided by a feedback circuit. An interface circuit allows operation of the circuit control device without discrimination on a power supply of either alternating or direct voltage or both. Life expectancy of the device is enhanced by several features including double break contacts with contact wiping and the provision of a floating output arm for the solenoid.

CROSS REFERENCE TO RELATED APPLICATIONS

The disclosure herein is also included in U.S. patent application Ser.No. (395,534), in the name of Aime J. Grenier; Ser. No. (395,167), inthe names of Aime J. Grenier and Lyle E. McBride; Ser. No. (395,174), inthe names of Aime J. Grenier and Robert W. Peterson; Ser. No. (395,169)in the names of Aime J. Grenier and Robert J. Bowen; Ser. No. (395,532)in the names of Aime J. Grenier and Hans G. Hirsbrunner; and Ser. No.(395,168), in the names of Aime J. Grenier, Robert W. Peterson, and OddLarsen; all filed on July 6, 1982 and assigned to the assignee hereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to circuit control systems and more particularlyto remotely operated circuit control systems.

2. Description of the Prior Art

In modern aircraft in order to reduce the weight and cost of heavy,expensive aviation cable between power supply busses and electric loadsvia the flight engineer's or pilot's station, it is known to useremotely controlled circuit devices such as remotely controlled circuitbreakers located near the power supply with small control unitspositioned in the cockpit and interconnected with the breaker itself bylight, inexpensive control wires in order to reduce the length of powerlead runs between the power bus equipment and the loads. These remotecontrol breakers function to protect against overloads (both of theshort-circuit and low level or ultimate trip types), as well ascontactors which are resettable and trippable from the control unit.

One such remote controlled circuit breaker is described and claimed inU.S. Pat. No. 3,651,436 which issued to Lawrence E. Cooper and Robert W.Peterson and is assigned to the assignee of the instant invention. Whilethat circuit breaker has been very effective and reliable, assembly ismore complex and time consuming than desirable thereby adding to thecost of the device. Further, there is a continuing need to decrease thesize and weight of such circuit breakers and to increase their lifeexpectancy. Another example is described and claimed in U.S. Pat. No.4,317,094 in which a solenoid and pawl arrangement can be used withconventional circuit breakers to make them remotely controllable. Theapplicability of this latter example is however, somewhat limited sincethe force levels required for lower current ratings due to the sizelimitations imposed by the airplane structure. That is, if it were to beused at current levels of up to 75 amperes for example, the size of thesolenoid required would be larger than acceptable.

SUMMARY OF THE INVENTION

Among the several objects of the invention may be noted the provision ofimproved remotely controlled circuit control devices which permitsubstantial economies in the reduction of cable weight and expense; theprovision of such devices in which power switching, overload sensing andprotection functions are provided in one unit located in a positionclose to the power source and the load being supplied and protected,while even smaller control units are positioned in the strategic andspatially limited area of the cockpit or flight engineer's console,there to provide the control and to indicate contact status conditions;the provision of circuit control devices of the type described whichhave improved rupture capacity as well as having increased reliabilityand longer life expectancy, yet are of reduced size and weight comparedto prior art devices; the provision of circuit control devices of thetype described which have a minimum number of adjustments or calibrationsteps required during assembly and which, in general, are more conduciveto low cost assembly techniques, the provision of circuit controldevices which combine contactor and breaker functions in one package,protect against all types of overloads and are inherently trip-free andthe provision of such circuit control devices which can be used withoutdiscrimination with a-c or d-c powder within prescribed ranges.

Briefly, a remote controlled circuit control device of this inventionincludes first and second load contact assemblies which are movablerelative to one another into a circuit engagement position and a circuitdisengagement position on alternate forward strokes of a single solenoidacting through a push-push mechanism. The push-push mechanism isoperatively connected to one of the load contact assemblies and a latchmechanism cooperates with the push-push mechanism to maintain the loadcontacts in the circuit engaged position when the push-push mechanism isreset and a thermal overload mechanism is operatively connected to thelatch mechanism and is adapted to unlatch the load contacts uponoccurrence of an overload condition. The push-push mechanism ismechanically coupled to several switches in such a manner that actuationof the switches is dependent upon the position of the said one of theload contact assemblies. One of these switches is a mode switch whichrelates the position of the load contacts to the logic circuit so that asolenoid drive pulse signal will enter a solenoid drive circuit only inthe correct sequence. When the breaker is closed (load contacts engaged)the pulse signal is allowed only in a trip circuit and when the breakeris open (load contacts disengaged) the pulse signal is allowed only inthe reset circuit. Another switch is an overload trip switch which isused to provide contact status feedback and coordination between theload contacts and the contacts of an indicator-control unit (ICU). Athird switch may be included to indicate contact status by actuatingother signal devices such as a pilot light or buzzer or to interfacewith other control circuits as may be desired. The device includes atrip free feature in which the contact assemblies are maintained out ofelectrical engagement for the duration of the energization of thesolenoid during a reset operation initiated by a manual closing of theICU. The load contacts close to complete the electrical circuit only onthe retraction part of the solenoid stroke cycle after the solenoidexcitation pulse is terminated. In order to increase life expectancy thecontacts are of the double break variety with contact wiping effectedupon movement of the load contact assemblies to the circuit disengagedposition. The solenoid is provided with a floating output arm toincrease its life expectancy.

The invention accordingly comprises the constructions hereinafterdescribed, the scope of the invention being indicated in the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, in which several of various possibleembodiments of the invention are illustrated,

FIG. 1 is a schematic diagram illustrating operational features of acircuit control system made in accordance with the invention;

FIG. 2 is an elevational view of a circuit control device made inaccordance with the invention and used in the system of FIG. 1;

FIG. 3 is a bottom plan view of the FIG. 1 device;

FIG. 4 is an electrical schematic diagram showing the circuitry embodiedin the circuit control device of FIGS. 2 and 3;

FIG. 5 is a vertical cross section taken on line 5--5 of FIG. 3 showingthe circuit control device in the contacts tripped, disengaged position;

FIG. 6 is a view similar to FIG. 5 but showing the device in thecontacts reset engaged position;

FIG. 7 is a vertical cross section taken on line 7--7 of FIG. 2 showingthe circuit control device in the contracts tripped disengaged positionand highlighting details of the overload trip mechanism;

FIG. 8 is a view similar to FIG. 7 but showing the device in thecontacts reset, engaged position;

FIG. 9 is a vertical cross section somewhat similar to FIG. 7 buthighlighting details of the pivotably mounted contact assembly andshowing an alternative mount for the microswitch actuator strip;

FIG. 10 is a horizontal cross section taken on line 10--10 of FIG. 2highlighting details of a motion transfer mechanism and the overloadtrip mechanism;

FIG. 10A is a perspective view of a stirrup element;

FIG. 11 is a horizontal cross section taken on line 11--11 of FIG. 2highlighting electrical connections of the internal power circuit;

FIG. 12 is an elevational view of the pivotably mounted contact seen inFIG. 9;

FIG. 13 is a top plan view of the movable contact bridge plate used inthe circuit control device;

FIG. 14 is a top plan view of a striker plate used in the circuitcontrol device;

FIG. 15 is a perspective view of the overload trip mechanism used in thecircuit control device;

FIG. 16 is a cross sectional view of a solenoid used in the abovecircuit control device;

FIG. 17 is a plan view of a hybrid-flex circuit including some of thecircuit elements shown in in FIG. 4 prior to folding and inserting intothe housing of the circuit control device;

FIGS. 18A through 18F show a portion of the indexing and latchingpush-push mechanism in two stable positions (tripped and reset) and fourtransition positions; and

FIGS. 19A through 19F are similar to FIGS. 18A-18F but showing analternate embodiment.

Corresponding reference characters indicate corresponding partsthroughout the views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, FIG. 1 illustrates operational featuresof a remote circuit control system made in accordance with the inventionin which a circuit control device 10, denoted by a dashed line 12 housesfirst and second load contact assemblies 14 and 16 respectively alongwith electrical and mechanical means to move the load contact assembliesinto circuit engaged and circuit disengaged positions. A remoteindicator/control unit (ICU), a circuit breaker 18 of the bimetalthermostatic type is disposed remotely from circuit control device 10,i.e., typically in the cockpit or flight engineer's console of anairplane and is adapted to couple a portion of the circuit controldevice 10 through connector 3 to ground through the bimetal thermostaticelement 18.1 in response to actuation by a actuating button PB1 of thecircuit breaker. The electrical means for moving the load contactsbetween the two positions comprises a solenoid drive 20, a mode switch22 adapted to connect either reset circuit 24 or trip circuit 26 tosolenoid drive 20, an optical coupler 28 coupling the reset and tripcircuits to the remote control unit 18, a contact status feedbackcircuit 30 and an electronic power supply 32.

The mechanical means for moving the load contacts between the twopositions include a so called push-push mechanism 34 operativelyconnected to load contact assembly 14 and adapted to be actuated bysolenoid drive 20, a latch mechanism 36 which cooperates with mechanism34 to maintain the load contacts in the circuit engaged position whenthe mechanism is reset, and a thermal overload mechanism 38 which isoperatively connected to latch mechanism 36 and is adapted to unlatchthe load contacts upon the occurrence of an overload condition. Loadcontact assembly 14 is mechanically coupled to several switches in sucha manner that actuation of the switches is dependent on the position ofload contact assembly 14. This mechanical coupling is represented inFIG. 1 by the dashed lines extending from contact assembly 14 to modeswitch 22 and overload trip switch 44. In general, the dashed lines inFIG. 1 extending between various components indicated a mechanicalcoupling, relatively fine solid lines indicate a signal circuit, heavysolid lines indicate the main power circuit and the medium heavy solidlines indicate feedback and drive circuits.

Also noted in FIG. 1 are T1 and T2, the line and load terminalsrespectively, connector 4 for auxiliary power, rectifying means D1 andD8 and connector 5 for connection to ground. With particular referenceto FIG. 3 connector module 40 is shown mounted on the bottom of controldevice 10 and includes connectors 3, 4, and 5 referred to above as wellas S1, S2, and S3 which are connectors for an auxiliary microswitch 42,provided for connection to some external indication circuit provided bythe user (i.e., the plane manufacturer). As seen in FIG. 1, S1represents a common contact connectable between contact S3 when the loadcontacts are in the contacts disengaged position and contact S2 when theload contacts are in the contacts engaged position. Auxiliary switch 42is mounted in control device 10 in such a manner that it is actuatedeach time load contact assembly 14 moves to its contacts engagedposition. Mode switch 22 and overload trip switch 44 are also mountedwith switch 42 for actuation by load contact assembly 14 as will beexplained in detail below.

The electrical means for effecting movement of the load contactsrelative to one another and for providing contact coordination is shownin FIG. 4. Points E1-E19 indicate points of connection on a flex-hybridcircuit shown in FIG. 17 to either hybrid circuit components or externalconnections to the circuit. Control circuit current is drawn from lineterminal T1 and passes through rectifying diode D1. Auxiliary or back upcontrol circuit power may be provided at connector 4, the currentpassing through rectifying diode D8 to point E12. An interface circuitto enable the use of either AC or DC voltage or both includes, inaddition to diodes D1, D8, a relay coil of relay RY1, a double pole,double throw relay which is serially connected to point E12 throughresistor R2. zener diode Z4, resistor R1, and blocking diode D2.Capacitor C1 is coupled across the relay coil and resistor R2 while azener diode Z5 is coupled across the coil of relay RY1. Relay RY1 isadapted to be energized by a selected voltage level attainable at therelay coil only when a voltage of sufficient magnitude is supplied at E3or E1. This sufficiently high voltage level is normally supplied in a-cbut not d-c applications so that operation of the relay RY1 is in effectdependent ot the type of electrical circuit with which the device isutilized, such as normal levels of 115 volts (alternating) or 28 volts(direct). Ballast resistors R3 and R21, serially connected to oneanother are connected between point E12 and point E5 with relay contactsK6 and K8 coupled across the ballast resistors. When the coil of relayRY1 is deenergized contact K6 and K8 are in engagement in effectshorting out resistors R3, R21. When the coil of relay RY1 is energized,contacts K8 and K7 move into engagement so that current will flowthrough ballast resistors R3, R21. Resistor R4 is connected between therelay contacts K6, K8 and a power supply circuit 32 with diode D4blocking current flow through resistor R4 from resistors R3, R21. DiodeD3 blocks current flow through resistor R4 from circuit elementsconnected at E-11.

Electronic power supply 32 provides a selected DC level for the logicportion of the circuit including reset circuit 24 and trip circuit 26and comprises zener diode Z1 connected in parallel with capacitor C2between point E11 and ground at connector 5 (point E4).

The reset and trip circuits 24 and 26 comprise a dual comparator circuitU1 which has a direct voltage level provided by power supply 32 betweenpins 8 and 4 respectively of reset operational amplifier U1a and tripoperational amplifier U1b. A voltage divider circuit comprisingresistors R5 and R8 is connected between the output of the power supply32 and ground to provide a reference voltage to the input pin 2 ofamplifier U1b and the input pin 5 of amplifier U1a. An RC timing delaynetwork comprises capacitor C3 connected between the power supply outputand the input pin 6 of amplifier U1a and resistor R7 connected betweenpin 6 and point E2 to be discussed below. Another timing delay networkcomprises capacitor C4 and resistor R6. Capacitor C4 is connectedbetween input pin 3 of amplifier U1b and ground while resistor R6 isconnected between point E2 and the output of power supply 32.

Point E2 is connected through pin 5 of optical coupler U2 to thecollector of the coupler's light responsive transistor, the emitter ofwhich is connected to ground through pin 4. The optical coupler's lightemitting diode is connected through pin 2 to connector 3 (and thus tothe ICU) and through pin 1 to resistor R19. The light emitting diode maydraw current through either diode D7 from E11 or through resistors R18and R19 from E-12.

The output pin 7 of amplifier U1a is connected to another RC timingcircuit comprising capacitor C5 and resistor R13 which in turn isconnected to ground. The junction between capacitor C5 and resistor R13,point E8 is connected to diode D11 which in turn is connected to thenormally closed (ready to reset position) contact of mode switch 22.Intermediate point E8 and diode D11 a charge enhancing circuit isdisposed comprising diode D10 connected to resistor R23 which is turn isconnected to the emitter of PNP transistor Q5 whose collector isconnected to ground. The base of transistor Q5 is connected to pointE19, the common terminal of mode switch 22.

Output pin 1 of comparator U1b is connected to RC timing circuitcomprising capacitor C6 and resistor R14 which in turn is connected toground. The junction of capacitor C6 and resistors R14, point E10 isconnected to the normally open (ready to trip position) contact of modeswitch 22.

The common terminal of mode switch 22 is connected through diode D12 atpoint E9 to an RC pulse extender circuit comprising capacitor C9 andparallel connected resistor R24, both connected to ground. Point E9 isserially connected to blocking diode D9, zener diode Z3, resistor R11and the base of NPN transistor Q2, the first of a two stage amplifierpair of transistors Q2, Q3. Resistor R15 is placed between the base oftransistor Q2 and ground while resistor R22 in placed between thecollector of transistor Q2 and point E5. The emitter of transistor Q2 iscoupled to the base of NPN power transistor Q3 whose emitter isconnected to ground and whose collector is connected to solenoid 20.1.Diode D5 is coupled across solenoid 20.1 to dissipate back EMF and toreduce stress on power transistor Q3 during the shut off period. Thisdiode also services to maintain current flow through the solenoid duringan operation on 400 Hz half wave excitation for the half of each cyclein which diode D1 blocks. The energy stored in the magnetic field of thesolenoid is thus used to extend current flow during the off part of eachcycle and reduce the force fluctuations in the solenoid output. Asnubber circuit for transistor Q3 comprises capacitor C8 connected onone side to diode D5 and on the other to diode D6 which in turn isconnected to ground with resistor R12 coupled across diode D6.

Contact status feedback circuit 30 extends between rectifiers D8, D1 andpoint E15 which is connectable to the indicator control unit 18 disposedin the cockpit which in turn is connectable to ground through thermalelement 18.1.

This circuit path comprises overload trip switch 44 which is in turnconnected to first and second parallel connected branch circuits. Thefirst branch comprises a positive temperature coefficient (PTC) elementP1 connected between switch 44 (point E13) and a main electrode of anSCR Q4 whose gate is connected to the common terminal K2 of relaycontacts RY1B which are controlled by the coil of relay RY1. Contact K4of relay contacts RY1B is connected through biasing resistor R20 topoint E13. Contact K3 is connected to the other main electrode of SCRQ4. The second branch circuit comprises a second positive temperatureresistor (PTC) element P2 connected between switch 44 and point E15.Both Both PTC elements are chosen to have the same anomaly temperature(in the preferred embodiment 130° C.) and are mounted so that they arethermally coupled to one another. Current flow through the parallel pathincluding resistors R18 and R19 is trivial and insufficient to cause ICUunit 18 to trip. when the overload trip switch 44 is closed, currentflow through the path including PTC elements P1 and P2 is sufficient tocause the bimetallic element in a closed ICU 18 to heat causing ICU 18to trip, opening the circuit to ground. In the event that ICU unit 18fails to open for any reason the PTC elements serve to limit the currentflow through the line leading to the unit 18 thereby protecting the linefrom overcurrent. and the power source from a continuous current drain.

Relay contacts K2-K4 of RY1B and K6-K8 of RY1A are shown in thedeenergized condition of the coil of relay RY1 which condition existswhen there is an absence of a sufficient voltage level required for suchenergization as occurs in the d-c operating mode.

The interface circuit is adapted to provide both the required drivepower for the solenoid 20.1 as well as the selected level of directvoltage for the logic portion of the circuit for any level of inputpower at terminal T1 and connector 4 between 18 to 32 volts DC and 104to 132 volts AC.

For an explanation of the operation of the circuitry it should be notedthat there are two stable conditions of the load contacts of circuitcontrol device 10, viz., the load contacts engaged, reset position, andthe load contacts disengaged, tripped position. As will be explained ingreater detail below in describing the various mechanical andelectromechanical components and operation of the device when the loadcontacts are in the engaged, reset position the overload trip switch 44is open and the mode switch 22 is in the ready to trip position and whenthe load contacts are in the disengaged, tripped position the overloadtrip switch 44 is closed and the mode switch 22 is in the ready to resetposition.

With regard to the contactor function, starting with the load contactsin the disengaged, tripped position when the pilot or other operatorwants to energize the load he closes ICU 18 by pushing button PB1. Inthe preferred embodiment ICU 18 is a small helf-ampere rated circuitbreaker, uncompensated for ambient thermal conditions. When ICU 18 isclosed it provides a path to ground from terminal T1 and connector 4through resistors R18, R19 and the light emitting diode of opticalcoupler U2. The transistor of coupler U2 then turns on and brings pointE2 to ground. Capacitor C3 charges through resistor R7, and when thevoltage at pin 6 of amplifier U1a drops below the reference voltage atpin 5, output pin 7 goes to a high voltage state, approximately equal tothe power supply output voltage at E11. This high voltage also occurs atpoint E8 but decays as capacitor C5 charges as current flow through C5,R13 and the parallel network connected at E-19 and, once the mode switchopens, through transistor Q5 which turns on when the mode switch opens.Since the mode switch is in the ready to reset position, the pulsepasses on to zener diode Z3. Diode Z3 helps to chop off the long delaytail of the pulse which would cause undesirable operation of transistorsQ2 and Q3 in a high loss area. If the voltage level is above an amountdetermined by diode Z3 selected to avoid nuisance tripping due to noiseand the like, transistor Q2 will be turned on for the duration of thepulse which in turn turns on transistor Q3 and allows current to passthrough solenoid 20.1 from ballast resistors R3, R21 if the main powersupply is a-c or through contacts K6, K8 of relay contacts RY1A if themain power supply is d-c. At the cessation of the pulse Q3 is turned offthereby deenergizing solenoid 20.1. The duration of the pulse isselected so that solenoid 20.1 is energized long enough to cause theload contacts to move to the contacts reset or engaged position afterthe mode switch opens as will be explained in greater detail below. Inorder to ensure that the pulse is of sufficient duration at lowexcitation voltages the pulse extender RC network of resistor R24,capacitor C9 is provided. This extends the pulse for a few millisecondssubsequent to the transfer of the mode switch to ensure that thesolenoid continues to drive through to the end of the stroke. At higherexcitation voltages this is not necessary since momentum carries themechanism through at the higher solenoid drive levels.

With the load contacts now in the reset, engaged position the modeswitch 22 is in the ready to trip position and trip switch 44 is open.This entire sequence takes approximately 70 milliseconds to complete.

When the operator wishes to disengage the load contacts he pulls up onpush button PB1 and opens the circuit through the light emitting diodeof optical coupler U2 which deeergizes the light emitting diode andturns off the coupler's transistor. Capacitor C4 charging now occursthrough resistor R6, and when voltage at pin 3 of amplifier U1b exceedsthe referenced voltage at pin 2 of the comparator the output pin 1 goesto a high voltage state, approximately equal to the power supply outputof E-11. This high voltage also occurs at point E10 but decays ascapacitor C6 charges as current flows through C6, R14 and the parallelnetwork connected at E19. Since the mode switch is now in the ready totrip position the pulse is passed on to the amplifier pair oftransistors Q2, Q3 to energize solenoid 20.1 for the selected pulseduration to move the load contacts mechanism back into the tripped,disengaged position. When the load contacts move to the disengagedposition, overload trip switch 44 closes, however no current passesthrough PTC elements P1 or P2 since the contacts of ICU 18 are open.

With regard to the circuit breaker function when an overcurrent occurs,a latch maintaining the load contacts in engagement releases and allowsa contact return spring, to be described infra, to move the loadcontacts to a disengaged position causing overload trip switch 44 toclose and the mode switch 22 to move to the ready to reset position.Current flows through switch 44 into one or both PTC elements P1, P2depending on whether relay RY1 is energized or not. In either case ICU18 is subjected to additional current which quickly causes thermostatelement 18.1 to heat, tripping and opening the ICU unit 18 and the pathto ground thereby coordinating the status of the ICU 18 contacts withthe load contacts and giving visual indication through the position ofpushbutton PB1. This also deenergizes optical coupler U2 and causespoint E2 to go to a relatively high voltage level. The outputs of thetwo operational amplifiers then "flip-flop" with U1a's going low andU1b's going high. However the pulse generated in the ready to tripcircuit is not passed to the solenoid drive circuit since the modeswitch 22 has opened the link. There is no switching pulse generated inthe ready to reset circuit since capacitor C5 is discharged to groundthrough U1a and in fact, point E-8 is temporarily even more negative.

If the ICU 18 should be closed by an operator while a fault conditionexists, the breaker will transfer to the latching position, the modeswitch will transfer and the load contacts will then engage on theretraction stroke of the solenoid. The overload circuit will cause thebreaker to unlatch and the load contacts to disengage within a fewmilliseconds after the contacts engage on the fault if a short circuitcondition exists or within a longer period for lower levels of overloadcurrent according to the required time-current values specified. Modeswitch 22 also will return to the ready to reset position and if thetrip time is short enough, as in a short circuit rupture, the voltagelevel at E-18 would still be sufficiently high when the mode switchtransfers to cause the solenoid drive circuit to be pulsed again therebyreclosing the load contacts on the fault with disastrous results. Toprevent this, a "pulse chopper" circuit branch comprising diode D10,resistor R23, and PNP transistor activates when the mode switch contactstransfer. Capacitor C5 then charges rapidly because of the increasedcurrent drawn through resistor R23 now effectively in parallel withresistor R13 and the voltage at E-8 is dissipated before mode switch 22reconnects the reset pulse circuit to the solenoid drive circuit. Thiseffectively cuts short the pulse from amplifier U1a and preventsreactuation of solenoid 20.1 with concomittant cycling of the systembetween the engaged and disengaged position.

The control circuit provides a selected time delay in power-upsituations through the input RC network of amplifiers U1a and U1b beforethe generation of a pulse in order to ensure that the relay contactsRY1A having transferred to the correct position before the solenoid isenergized otherwise excessive current could cause relay failure ordamage to power transistor Q3.

It will be noted that on direct voltage, power for the logic portion ofthe circuit is derived through diodes D1, D8, contacts K6, K8 resistanceR4 and diode D3, while solenoid power is derived through diodes D1, D8,contacts K6, K8, and diode D4. On alternating voltage contacts K8 and K7are in engagement forcing current through ballast resistors R3 and R21for the solenoid power which is blocked from power supply circuit 32 bydiode D3. On a-c power, the logic portion of the circuit power isobtained through diode D2, resistor R1, zener Z4, capacitor C1, resistorR2, zener diode Z5, and the coil of replay RY1 to the power supplycircuit 32.

Turning now to the mechanical and electromechanical features and withparticular reference to FIGS. 5-8 circuit control device comprises ahousing 45 of suitable electrically insulative material in which isdisposed a push-push mechanism 34 for actuating the circuit controldevice and indexing the load contact assemblies alternately into acircuit engaged, reset position and a circuit disengaged, trippedposition. Mechanism 34 comprises a stationary, cylindrical bushing orsleeve 46 having a radially extending flange 46.1 captured betweenmating upper and lower portions 48.1, 48.2 of a base 48 of electricallyinsulative material having good physical strength and arc resistancecharacteristics at high temperatures, such as diallylphthalate orthermosetting polyester, mounted in housing 44.

Telescopically and slidably mounted within sleeve 46.1 is a cylindricalsleeve 50 which serves as a carrier for latch balls 52 and movablecontact bridge plate 54. A contact bridge plate return spring 56 isdisposed between step 46.2 of bushing 46 and the bottom surface ofbridge plate 54 and is adapted to place an upward bias on the bridgeplate. Three bores 50.1, equally spaced in the lower portion of sleevercarrier 50 each of which being adapted to receive therein a latch ball52 have a diameter somewhat greater than the wall thickness of thesleeve adjacent the bore. Stationary bushing 46, at its lower endportion, is formed with a recess 46.3 defined in part by a cammingsurface 46.4, which recess is adapted to receive a portion of latchballs 52 therein as shown in FIG. 6.

Telescopically and slidably received within carrier sleeve 50 isgenerally cylindrical main plunger 58 having at its lower end a latchrecess 58.1 defined in part by a latch retainer surface 58.2. Mainplunger 58 is formed with a longitudinal extending bore 58.3 incommunication with its upper end and a plurality of radially extendingbores 58.4 equally spaced about the periphery of plunger 58 incommunication with bore 58.3. An index ball 60 having a diametersomewhat greater than the wall thickness of the main plunger 58 adjacentbore 58.4 is received in each radially extending bore. A groove 58.5 isformed about the circumference of plunger 58 adjacent its upper end andis adapted to receive therein a spring 92.2, to be discussed below,which is adapted to place an upward bias on main plunger 58.

Telescopically and slidably received within bore 58.3 of main plunger 58is a generally cylindrical index plunger 64 having a trip index portion64.1 at its lower end and a reset index portion 64.2 above and adjacentthe trip index portion. Reset index portion 64.2 includes a recess 64.3defined in part by reset surface 64.4. Index plunger 64 is formed with aflange 64.5 at its top portion which is used as a seat for spring 66disposed between flange 64.5 and the top face surface of main plunger 58to place on upward bias on index plunger 64.

Main plunger 58 is also telescopically and slidably received in agenerally cylindrical sleeve, trip/reset cap member 68. A recess 68.1 isformed in the bottom portion of the bore of cap 68 which is defined inpart by camming surface 68.2. As can be seen from FIG. 6 when recess68.1 of cap member is aligned with bores 58.4 and trip index portion64.1, index balls 60 are maintained in recess 68.1 of the cap member andas seen in FIG. 5 when bores 58.4 are aligned with the reset recess 64.3cap 68 is allowed to slide downwardly relative to plunger 58 with thetop surface portion 68.3 of the bore of cap 68 maintaining index ballswithin reset recess 64.3.

A striker plate 70 is fixedly mounted to trip/reset cap member 68 asindicated by key 72 and is adapted to contact stop surface 74 formed inhousing 45 to limit upward movement of striker plate 70 and cap member68.

A pair of contact members 76, 76 are pivotably mounted in base 48 bycapturing a pivot pin, 76.1 (FIGS. 7, 8) between base portions 48.1 and48.1. As best seen in FIGS. 7 and 8 contact member 76 is pivotablymounted at one end 76.2 and has at its opposite end a toe portion 76.3.Intermediate its ends a protrusion 76.4 forms a spring seat for apivotable contact return spring 78 which spring extends between contactmember 76 and the bottom portion 48.2 of base 48 so that, as seen inFIGS. 7 and 8 a clockwise bias is placed on contact member 76. Referencemay also be had to FIG. 12 for an elevational view of one of thepivotable contact members 76.

Contact members 76 are oriented in opposite directions to one another toprovide mechanical symmetry relative to the push-push mechanism 34. Thatis, as seen in FIGS. 7 and 8 the pivoted end 76.2 is on the right sideof the longitudinal axis 34.1 of the push-push mechanism 34 while othercontact member 76 hidden behind the push-push mechanism has its pivotedend to the left of the longitudinal axis. This orientation can also beseen in FIGS. 5 and 6 where toe 76.3 is seen on the left of thelongitudinal axis 34.1 and end 76.2 is seen on the right of axis 34.1.

Contact plate 54, see in particular FIG. 13, is generally rectangular intop plan view and is configured to orient the contact surfaces so thatthey will be in alignment with the contact surfaces of pivotable contactmembers 76. To that end first and second legs 54.1 and 54.2 extend alongtwo opposite sides 54.3, 54.4 of a main body portion 54.5 and are joinedto body portion 54.5 at two diametrically opposed corners 54.6 and 54.7respectively. Electrical load contacts 54.8 of suitable contactmaterial, such as a silver, tin oxide and indium oxide, are mounted atthe distal free end of legs 54.1 and 54.2. It will also be noted that atab 54.9 projects out from the main body portion 54.5 which is slidablyreceived in a vertically extending groove 48.4 formed in base 48 inorder to maintain the proper orientation of contact plate 54 so thatcontacts 54.8 mate with contacts 76.5 of pivotable contact members 76.

Striker plate 70, shown in plan view in FIG. 14, is configured generallyas a rectangle with legs 70.1 and 70.2 extending beyond the main bodyportion 70.3. A tab 70.4 projects outwardly from one end face of leg70.1 while a similar tab 70.5 projects outwardly from the oppositelydisposed end face of leg 70.2.

A link 80 formed of suitable electrically insulative material such asthat used for base 48 operatively connects striker plate 70 andpivotable contact members 76. As seen in FIG. 9, link 80 is an elongatedbar shaped element having an aperture 80.1 on its lower end into whichtoe 76.3 of the pivotable contact member projects. At its upper end link80 is formed with an elongated lost motion slot 80.2 into which tab 70.4or 70.5 of striker plate 70 extends. As seen in FIG. 9, when strikerplate 70 moves downwardly once it hits the bottom surface defining slot80.2 of link 80 continued downward motion causes counterclockwisepivotal movement of contact member 76.

As seen in FIGS. 5 and 6, downward movement of contact bridge platecarrier 50 is limited by shoulder 50.2 of carrier 50 contacting the topdistal face portion 46.5 of stationary sleeve 46. As will be explainedin greater detail below, when trip/reset cap member 68 is caused tostroke downwardly carrying striker plate 70 along with it, it causespivotable contact members 76 to pivot downwardly preventing circuitengagement of contacts 54.1, 54.2 of contact bridge member 54 withrespective contacts 76.5, 76.5 of contact members 76 until striker plate70 starts to move upwardly in the lost motion slot 80.2 thereby allowingcontact members 76 to pivot clockwise under the influence of springs 78into circuit engagement of movable contacts 54.1, 54.2 with respectivepivotable contacts 76.5 and 76.5, with the contact bridge plate 50latched in its lower position as will be explained below.

Upon unlatching of contact bridge plate 50 upward movement results incontact wiping motion due to the pivoting motion of contact members 76to help keep the contact surfaces clean.

Link member 80 is formed with an arc extinguishing grid 80.3 disposedintermediate slots 80.1 and 80.2 so that the arc grid will be adjacentthe contacts upon circuit engagement and disengagement.

Trip/reset cap member 68 is formed with a pair of horizontally extendingslots 68.4 on two opposite sides of its periphery (FIGS. 7 and 8). Slots68.4 facilitate connection of a motion transfer mechanism operativelyconnecting solenoid 20.1 and trip/reset cap member 68. The motiontransfer mechanism includes a solenoid lever 82 pivotably mounted on pin82.1 mounted in the walls of housing 44. Lever 82 is formed with a pairof arms 82.2 (FIGS. 7, 8, and 10) which mount at the free distal endsears 82.3 each of which is adapted to slidingly fit within a respectivegroove 68.4 of trip/reset cap member 68. On the opposite free endportion 82.4 an axially adjustably mounted member 82.5 having a curvedsurface portion 82.6 is aligned with a generally flat head 20.2 of anoutput arm 20.3 of solenoid 20.1. The position of curved surface portion82.6 can be adjusted relative to the top of solenoid 20.1 to therebyadjust the effective length of the stroke of arm 20.3. This adjustmentrelates the stroke of the solenoid to the full stroke position of themechanism during the reset operation. In order to use the availableoutput of the solenoid to full advantage, the lever adjusting screw 82.5is set so that both the mechanism at full stroke and the core inside thesolenoid "bottom out" simultaneously. A solenoid lever spring 82.7 ismounted on pin 82.1 and adapted to react against housing 45 to place acounterclockwise bias on the lever which tends to maintain trip/resetcap 68 in its raised or upper position.

The force of spring 82.7 acting through ears 82.3 is sufficientlygreater than the force exerted by spring 66 which reacts between indexplunger 64 and main plunger 58 to provide a resultant upward bias ontrip/reset cap 68. As seen in FIG. 16, the curved surface on the leveradjusting screw can be provided by using a ball bearing 82.8 mounted ina socket 82.9 at the end of solenoid lever 82. With particular referenceto FIG. 16 solenoid 20.1 has a core 20.4 having a longitudinallyextending bore 20.5 extending essentially the length of core 20.4 buthaving a closed end. Core extension 20.3 has a diameter selected to besufficiently smaller than the bore 20.5 that the extension loosely fitstherein so that it is free to wobble. Pole piece 20.6 is formed with abore 20.7 through which core extension 20.3 extends. The wobble motionof core extension 20.3 is limited by the side wall of bore 20.7 which inturn prevents the top portion 20.8 of core 20.4 from striking the sidewall of sleeve 20.9 which would cause gouging, increased friction andshortened life. To further enhance longevity sleeve 20.9, core 20.4 andcore extension 20.3 are preferably formed of or coated with materialshaving low friction and good wear characterisitics.

Mounted in housing 45 beneath the central stack of the push-pushmechanism 34 are three microswitches referred to above, overload tripswitch 44, mode switch 22 and auxiliary switch 42 having, respectively,actuating buttons 44.1, 22.1, and 42.1. A flexible actuator strip 84 isdisposed intermediate the switches and the push-push mechanism 34 withone end seated at 45.1 of housing 45 and with an opposite end adapted toengage a pair of actuator pins 84.1 (one is shown in FIG. 9) which areslidably disposed in bores 48.3 of base 48 aligned with the bottomsurface 50.3 contact bridge plate carrier 50 so that when bridge platecarrier 50 is in its lower position the actuating buttons 44.1, 22.1,and 42.1 are depressed by actuator strip 84 which is depressed bycarrier 50 through pins 84.1 and when carrier plate is in its upperposition the actuating buttons 44.1, 22.1, 42.1 are in their upperposition. Thus when contact carrier bridge plate 54 is in its contactsengaged, lower position the switches 44, 22, and 42 are in one state ofactuation and when the contact carrier bridge plate 54 is in thecontacts disengaged, upper position the switches are in the oppositestate of actuation.

With particular reference to FIGS. 7, 8, 10, and 15 the structureproviding the overcurrent, circuit breaking function comprises a firstactive or load current carrying bimetal member 86 having a first end86.1 anchored in base 48 and extending in an upward direction and havinga second end 86.2 attached to a block 86.3 composed of electricallyinsulative material. Bimetal member 86 is formed from an elongated striphaving a first end connected to a crimp terminal 86.4, the stripextending back and forth between base 48 and block 86.3 and terminatingat a second end connected to a crimp terminal 86.5. Block 86.3 is formedwith a projection 86.6 which is slidingly received in a slot 88.1 at oneend surface of latch plate 88. Latch plate 88 end 88.5 is bentdownwardly approximately 90° relative to legs 88.2 and 88.3 to form alatch surface 88.6. Preferably that portion of end surface 88.5contiguous to latch surface forms an angle of slightly less than 90°with the horizontal to ensure a positive release of trip arms disposedon the latch surface as will be explained below. A tab 88.7 projectsupwardly from end 88.5 in the middle portion thereof separating latchsurface into two portions.

A second passive or ambient compensating bimetal member 90 has one endanchored in base 48 and extends in a direction parallel to that ofbimetal member 86 with the push-push mechanism 34 interposed between thetwo bimetal members 86, 90. At the free distal end 90.1 a bracket 90.2is attached extending across slot 90.3 and is adapted to mount acalibrating member 90.4. Member 90.4 has a reduced diameter portion 90.5(see FIG. 10) which extends through a slot in bracket 90.2 and athreaded portion is received in a threaded bore in tab 88.7 so thatturning of the member will adjust the position of latching surface 88.6relative to ambient compensating bimetal 90. A pair of trip arm members92 are mounted on and keyed to bushings 92.5 which are in turn fixed topin 92.1 mounted in block 86.3 by soldering and/or interference fits onknurled ends of the pin. A pair of springs 92.2 mounted on bushings 92.5have one end fixed in a slotted portion 92.3 of bushing 92.5. The otherends 92.4 of springs 92.2 are adapted to be received in the groove 58.5formed on main plunger 58 and are adapted to place an upward bias on theplunger when the trip arms 92 are maintained in their latched positionby latch surfaces 88.6.

Alternatively a generally U-shaped stirrup element 92.5 (see FIG. 10A)may be placed in groove 58.5 defined in plunger 58, element 92.5 havingturned over ends 92.6 adapted to capture ends 92.4 of latch springs92.2.

As ambient temperature changes causing deflection of load currentbimetal 86 a corresponding deflection occurs in ambient compensatingbimetal member 90 so that there is no motion of latch surfaces 88.6relative to trip arms 92; however when an overcurrent conditions occursin the load circuit causing further deflection of load current bimetal86 it will pull trip arms 92 away from latch surfaces 88.6 until they nolonger are maintained in the latched position and plunger 58 is allowedto descend since its upward bias is then removed and there is positivedownward bias from index plunger spring 66 and the reaction of latchballs 52 on latch surface 58.2 of the main plunger.

With reference to FIG. 11 terminal T2 is connected to pigtail 94.1 whichis connected at 86.4 to one end of current overload bimetal member 86while the other end of bimetal member 86 is connected at 86.5 to pigtail94.2 which extends and is attached at 94.3 to end 76.2 of pivotablecontact member 76. End 76.2 of the other of the pair of pivotablecontact members 76 is connected to pigtail 94.4 at 94.3 which pigtailextends to terminal T1. In the preferred embodiment the pigtailassemblies are resistance brazed to the bimetal member, contact membersand terminals with wire wraps crimped onto the pigtails to limit frayedor loose wire strands. The crimp connectors are formed of silver solderbrazing material to facilitate this operation.

The electrical circuitry described supra is mounted on portions 96.1,96.2 of a flexible circuit 96 which are received in grooves in housing45. Prior to folding and inserting into housing 45 the location ofvarious components is shown in FIG. 17. The following components listedin Table 1 were used in making a circuit control device in accordancewith the invention:

                  TABLE 1                                                         ______________________________________                                        Q2   NPN Transistor     R1     500  ohms 11/2w                                     A5T5058 300V, 150 m Amp                                                  Q3   NPN Transistor     R2     2K   ohms 1/2w                                      TIP 161 300V, 10 Amp                                                     Q4   SCR 7A 400V        R3     4    ohms 11/2w                                     RCA S2600D                                                               Q5   PNP Transistor     R4     270  ohms 1/2w                                      A5T2907A           60V, 600 m Amp                                        U1   TI LM 158JG        R5     33K  ohms 1/8w                                      Dual Operational Amplifier                                               U2   O.C.I. Integrated Circuit                                                                        R6     68K  ohms 1/8w                                      TI 4N24                                                                  Z1   SX30, 30V, 5W Zener                                                                              R7     56K  ohms 1/8w                                 Z3   1N753A 6.2V, 400 mW Zener                                                                        R8     33K  ohms 1/8w                                 Z4   SX24 24V, 5w Zener R11    1K   ohms 1/8w                                 Z5   SW30, 30V, 5w Zener                                                                              R12    1 M  ohms 1/8w                                      (DPDT)                                                                   RL1  Relay-Teledyne 412-26                                                                            R13    33K  ohms 1/8w                                 D1   1N5619 600V, 1 Amp R14    4.7K ohms 1/8w                                 D2   1N5619 600V, 1 Amp R15    100K ohms 1/8w                                 D3   1N5619 600V, 1 Amp R18    15K  ohms 1/4w                                 D4   1N5619 600V, 1 Amp R19    6.8K ohms 1/4w                                 D5   1N5619 600V, 1 Amp R20    1K   ohms 1/4w                                 D6   1N5619 600V, 1 Amp R21    4    ohms 11/2w                                D7   1N5619 600V, 1 Amp R22    470  ohms 1/4w                                 D8   1N5619 600V, 1 Amp R23    510  ohms 1/4w                                 D9   1N914   75V, 10 Amps                                                                             R24    200K ohms 1/8w                                 D10  1N5619 600V, 1 Amp C1     3.6  μf                                                                              125 V                                D11  1N5619 600V, 1 Amp C2     6.8  μf                                                                              35 V                                 D12  1N914   75V, 10 m Amp                                                                            C3     1    μf                                                                              50 V                                 P1   130° C. PTC C4     1    μf                                                                              50 V                                      5.5-9.5 ohms 28 VDC                                                      P2   130° C. PTC C5     3.3  μf                                                                              50 V                                      23-35 ohms 170 VAC                                                                               C6     3.3  μf                                                                              50 V                                                         C8     .001 μf                                                                              200 V                                                        C9     .68  μf                                                                              50 V                                 ______________________________________                                    

With particular reference to FIGS. 18A to 18F, operation of thepush-push mechanism 34, or central stack will be explained. In FIG. 18aand FIG. 18b an alternative form 58' of main plunger 58 is showncomprising an upper portion 58.6 fixedly joined to lower portion 58.7(see Ready to Reset position of FIG. 18A) which is functionallyequivalent to the one piece plunger shown in FIGS. 5-8 but more easilyfabricated.

In the initial, contacts open, read to reset position the main plunger58' is maintained in its upmost position under the influence of latchmember spring 92.2 and contact return spring 56. The striker plate 70 isin its upmost position, limited by the striker plate stop 74 under theinfluence of the solenoid lever spring 82.7 and the contact returnspring 56. The indexing plunger 64 is in its uppermost position limitedby the top of the casing 45 under the influence of the indexing plungerspring 66.

With particular reference to FIGS. 5-8, when the ICU 18 is closed, itcauses a current pulse to flow through the solenoid 20.1, this causesthe solenoid core extension pin 20.3 to hit the lever 82 and pivot itagainst the bias of the lever spring 82.7 and forces the trip/reset cap68 downwardly through the lever inserts 82.3. As seen in FIG. 18B, fullreset stroke, the camming surface 68.2 of the trip/reset cap 68 forcesthe indexing balls 60 into the reset recess 64.2 of the indexing plunger64. The bottom surface of the cap 68, in contact with the top surface ofthe contact bridge carrier 50, forces it downwardly until either thecontact bridge plate hits the boss of the base 48.1 or the carrier 50hits the bushing 46, the trip/reset cap 68 sliding by the indexing balls60 positioned in the reset recess. While the latch balls 52 force themain plunger 58' downwardly, the indexing balls force the indexingplunger 64 downwardly, the ball latch surface 58.2 camming the latchballs into the bushing recess 46.3. As the contact bridge carrier 50descends the bottom surface contacts the actuator pins 84.1 and forcesthem and the actuator 84 down thereby actuating switches 44, 22, 42 asbest seen in FIG. 9. The trip/reset cap mounts the striker plate so thatas the cap moves downwardly its motion is transferred to the pivotablymounted contact members 76 through links 80 pivoting them away from theapproaching contact bridge plate 54 mounted on the carrier therebymaintaining a selected gap between the contact bridge plate and thepivotable contacts member during the reset stroke. Lost motion slot 80.2allows striker plate 70 to move unimpeded, and hence the solenoid tostroke unimpeded by pivotable contact return springs 78 until the latterportion of the solenoid stroke when its push is highest at the moreefficient, nearly closed magnetic circuit condition.

The solenoid is deenergized once the mode switch transfers so that whenthe plunger reaches its full stroke shown in FIG. 18B, the downwardforce exerted through the lever inserts 82.3 is removed and the upwardbias of the pivotable contact springs 78 and contact bridge returnspring 56 cause the carrier to move upwardly until the latch balls 52,maintained in the bushing recess 46.3 by ball latch retainer surface58.2, limit further upward movement through the camming surface 46.4 ofbushing 46. The striker plate 70 and trip/reset cap 68 continue to moveupwardly under the influence of solenoid lever spring 82.7 and contactreturn springs 78 through the two links 80 until the movable contactsengage with those on contact bridge plate 54, the indesx balls 60 movinginto recess 68.1 of the trip/reset cap 68 as best seen in FIGS. 18C and18D. The indexing plunger 64 also moves upwardly under the influence ofspring 66.

The main plunger 58' is limited in its upward movement through latchballs 52 and surface 46.4 of bushing 46 and 58.2 of main plunger 58'.Index plunger 64 continues to move upwardly with index balls 60maintained in recess 68.1 of trip/reset cap 68 by trip index surfaceportion 64.1 of index plunger. (FIG. 18D).

FIG. 18D, Ready to Trip position is the stable load carrying positionwith the contacts latched in the closed or engaged position. Strikerplate 70 is at its uppermost position biased against stop surface 74 andthe index plunger 64 is biased against the housing top so that indexballs 60 are aligned with trip index portion 64.1 whereas in the FIG.18, Ready to Reset position index balls 60 are aligned with reset indexportion 64.2.

When the solenoid is actuated by another pulse caused by opening of ICU18, trip/reset cap 68 is again caused to move downwardly. However, itcannot slide by index balls 60 as it did in moving from FIG. 18A to FIG.18B due to the alignment of trip index portion 64.1 of index plunger 64.Downward movement of cap 68 therefore now transfers motion throughcamming surface 68.2, index balls 60 to main plunger 58' which moveslatch retainer surface 58.2 downwardly so that latch balls 52 aresqueezed out of recess 46.3 into latch recess 58.1 under the influenceof contact return spring 56 and pivotable contact spring 78.

Trip/reset cap member 68, contact bridge member 54, main plunger 58',and index plunger 64 now are free to return to their FIG. 18A positionunder the influence of the several springs.

When the device is in the FIG. 18D engaged contacts position and athermal overload occurs due to a fault condition causing excessivecurrent to pass through bimetal member 86, the upper portion of bimetalmember 86 will bend to the left as viewed in FIGS. 7 and 8 until triparms 92 are no longer supported on latch surface 88.6. This actioneffectively removes the upward bias of trip arm springs 92.2 since pin92.1, to which the springs are keyed, is allowed to move in a clockwisedirection now that springs 92.2 no longer have anything against which toreact. Thus main plunger 58' is biased downwardly by index plungerspring 66 and the reaction of latch balls 52 against surface 58.2allowing latch balls 52 to squirt out into the annular latch recess58.1. It will be seen that the downward push of latch balls 52 onsurface 58.2 of plunger 58' is a function of the angle that surface 58.2forms with the vertical, the diameter of balls 52, the amount of offsetin bushing 46, friction and the spring forces of springs 56 and 78. Oncethe load contacts have separated the contact return spring 56 moves thecontact bridge plate 54 upwardly which picks up main plunger 58' andtrip arms 92 and turns them to the FIG. 18A position with the trip arms92 held above latch surface 88.6.

From the above description it will be noted that the status of the loadcontacts, whether they are in the circuit engaged or disengaged positioncan be determined by noting the position of main plunger 58'; when thecontacts are in the circuit engaged position plunger 58' is down andwhen the contacts are in the circuit disengaged position plunger 58' isup. When main plunger 58' is up the latch balls are receivable in thereset index recess 64.2 and when plunger 58' is down the latch balls arealigned with trip index portion 64.1. Thus the position of the indexplunger 64 relative to the index balls 60 determines the indexingsequence.

FIGS. 19A-19F show a modification of the FIGS. 18A-18F embodiment of thepush-push mechanism. In this modification main plunger 58" is providedwith an open bottom end 58.8 formed with an inwardly, radially extendingflange 58.9. Telescopically and slidably received within thelongitudinally extending bore of plunger 58" is a latch pin 98 which hasa head portion 98.1 having a sufficiently large diameter that flange58.9 limits outward movement of the latch pin 98 relative to plunger58". A ball latch retainer 98.2 is mounted on latch pin 98 and ismovable between a first stepped stop surface 98.3 and a second stopsurface 98.4 formed by the top surface of a latch spring retainer 98.5fixedly mounted on latch pin 98. Latch spring 98.6 is received on a seat98.7 of spring retainer 98.5 and extends between retainer 98.3 and thebottom surface of ball latch retainer 98.2 placing an upward bias on theball latch retainer.

It will also be observed that an O-ring 100 is shown disposed about theperiphery of main plunger 58" and is adapted to absorb impact forcestransmitted between plunger 58" and contact bridge plate carrier 50. TheO-ring of course may also be used in the FIGS. 18A-18F embodiment.Another modification included in the FIGS. 19A-19F embodiment but usefulin either version is the provision of a recess 64.6 at the trip indexportion 64.1. It will be observed that trip index recess 64.6 is shallowrelative to reset index recess 64.2 and is provided to obtain a morepositive indexing action, particularly on applications in which thepower source voltage is at the high end of the range of voltages withwhich the circuit control device can be used. This recess prevents theindexing plunger from slipping past the ball under high momentum andimpact conditions occurring during trip operations at high voltagesolenoid drive conditions which otherwise might convert what hadoriginally started as a trip operation into a reset operation.

The operation of the push-push mechanism of FIGS. 19A-19F is verysimilar to that of FIG. 18A-18F thus the entire description will not berepeated. However in relation to the trip pin 98 it will be noted thatwhen trip/reset cap 68 moves downwardly upon energization of thesolenoid, force is transmitted to contact plate carrier 50 forcingcarrier 50 and latch balls 52 downwardly. Continued downward movementresults in latch balls 52 hitting latch retainer surface 98.8 forcingball latch retainer 98.2 downwardly against the bias of latch spring98.6 which absorbs some of the impact forces; until retainer 98.2bottoms out against stop surface 98.4. Continued downward movementforces main plunger 58" down from FIG. 18A to FIG. 19B with latch balls52 being cammed into latch recess 46.3 by latch retainer surface 98.8.

Contact bridge plate carrier bottoms there against bushing 46, or bridgeplate 54 hits housing hub portion 48.1 with the contacts kept out ofengagement through link 80 until the end of the stroke of the mechanismwhen, with the termination of the solenoid pulse caused by the transferof the mode switch, carrier 50 and bridge plate 54 move upwardly to theFIG. 19C position with surfaces 46.4 of latch recess 46.3 and 98.8 ofretainer 98.2 preventing further upward movement. The bias on plunger58" provides the force to maintain the balls in the latch recess.overcoming their reaction against the ball latch caused by return spring56 and pivotable contact springs 78.

Trip/reset cap 68 then continues its upward movement to the FIG. 19Dposition allowing the contacts to go into the circuit engaged position.

Upon the next energization of the solenoid with index balls 60 alignedwith the trip index portion (recess 64.6) of index plunger 64 downwardmovement of trip/reset cap 68 will cause camming surface 68.2 totransmit its motion to plunger 58" through index balls 60 (FIG. 19E)moving plunger 58" and carrier 50 to the FIG. 19F position. Aftertermination of the driving pulse, the solenoid retracts allowing capmember 68, main plunger 58", and contact plate carrier 50 to come backas a unit urged by the several springs. When latch balls 52 strikecamming surface 46.4 of the detent in bushing 46, they are cammed out ofthe detent into the annulus between the interior wall of sleeve 50 andlatch pin 98 since the shoulder of flange 58.9 no longer places anupward force on latch pin 98 allowing ball latch 98.2 to be easilydepressed and presents no opposing reaction to the balls escaping thedetent.

Latch retainer 98 is advantageously formed with the bottom portionconfigured as the frustrum of a cone and the top portion configuredessentially as half of a sphere to optimize consistent camming actionthrough surface 98.8. Although shown as movable between stops 98.3 and98.4 it is within the purview of the invention to mount latch retainer98.2 fixedly on latch pin 98 if so desired.

This type of flexible latch includes several advantages. The floatingsuspension allows better self-alignment of the four balls (since thesurface of the ball latch 98.8 which actually contacts the three balls52 in the ball carrier is spherical). Further, the latch retainer orball 98.2 is free to and does turn with pin 98 so that wear isdistributed around the contact periphery and deterioration of thesurface is avoided. This is very helpful in maintaining the proper forcereaction, especially in overload trip operation. Yet another advantageis the fact that the spring loaded latch is superior in vibrationcharacteristics since it allows some amplitude of vibration of the mainplunger in vibratory excitation while still maintaining force on thethree balls 52.

By way of summary and with particular reference to FIG. 1, the contactassemblies 14, 16 are either in circuit engaged or circuit disengagedpositions. Circuit control device 10 operates to transfer from one ofthese positions to the other and indicates the position via ICU unit 18.Transferring from the circuit disengaged to the circuit engaged positionis accomplished by closing ICU unit 18. This switches optical coupler28, energizes solenoid drive 20 through reset circuit 24 and mode switch22, moves the contact assemblies to the engaged circuit position,latches the device in that position, operates auxiliary switch 42 anddeactivates the feedback circuit to ICU unit 18. The feature of thecontact assemblies moving into the circuit engaged position only afterthe activating pulse is terminated and the solenoid is retractingobviates the possibility of the solenoid holding the contacts closedduring an overload for the duration of the activating pulse.

Transferring from the circuit engaged to the disengaged position isaccomplished by an operator by opening ICU unit 18 which switchesoptical coupler 28, energizes solenoid drive 20 through trip circuit 26and mode switch 22, unlatches the device, moves the contact assembliesto the circuit disengaged position with the pivotable contact members 76wiping across the surface of the movable contact 54.1 to help maintainthem clear of contaminants, operates feedback circuit 30 to ICU unit 18(this is redundant since ICU 18 is already open) and returns thepush-push mechanism to the ready-for-reset position.

Trip operation by a circuit overload effects movement of the contactassemblies to the circuit disengaged position by actuating thebimetal-operated thermal overload mechanism 38 which unlatches thedevice, moves the contact assemblies to the circuit disengaged position,operates auxiliary switch 42, activates feedback circuit 30 to ICU unit18, returns the mechanism 34 and mode switch 22 to the ready for resetposition and opens ICU unit 18. Device 10 cannot be reset until thefault condition has been cleared and thermal overload mechanism 38 coolssufficiently.

As noted supra, ICU unit 18 serves not only as a remote actuator fordevice 10 but also as an indicator for the power or load contact status,therefore ICU unit 18 and device 10 must correlate regarding circuitengaged and disengaged positions. Closing of ICU unit 18 moves contactassemblies 14, 16 into the circuit engaged position while opening of ICUunit 18 moves contact assemblies 14, 16 into the circuit disengagedposition. An overload trip of device 10 results in opening of ICU unit18. Further, after a total power loss the paired units automaticallyassume the same circuit engaged or disengaged position upon restorationof power. If the two units are in the same position when power isrestored, no action occurs. However, if ICU unit 18 is open and device10 is in the circuit engaged position device 10 will move to the circuitdisengaged position when power up occurs and conversely if ICU unit 18is closed and device 10 is in the circuit disengaged position, device 10will move to the circuit engaged position on power up.

While the above described circuit control system is operable on eitheralternating or direct voltage on either main or auxiliary power withremote operation and indication via ICU unit 18, it is within thepurview of the invention to make use of only certain ones of itsfeatures. For example, the system can be used without auxiliary switch42. The system does not require auxiliary or back up power and, byomission of electronic components required by the universal (alternatingor direct current) device, the unit may be used on either direct currentor alternating current when the universal application feature is notdesired resulting in a lower cost because of the reduction in componentcost. Further, it can be used without a feedback circuit for loadcontact status indication. It is possible to provide remote operation byswitching another circuit input to ground, such as point E-2, FIG. 4,using whatever interface is appropriate to the particular application,such as a toggle switch, transistor and so on. In certain applicationsthe degree of isolation needed may not require the use of opticalcoupler 28. In certain applications it may be desired to do without theelectronic circuit and operate the device by a pulse delivered directlyto the device by the user's control circuit.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above described constructionswithout departing from the scope of the invention, it is intended thatall matter contained in the above description as shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

We claim:
 1. A circuit control system comprising first and second loadcontact assembly means, the first load contact assembly means beingmovable between contacts reset engaged and contacts tripped disengagedpositions with the second load contact assembly means,motor means forcausing movement of the first contact assembly means in a firstdirection to alternately effect contacts engagement and contactsdisengagement, means for latching the first contact assembly means inthe contacts engaged position, and electrical circuit means forenergizing the motor means for moving the first contact assembly in thefirst direction including a single pole, double throw mode switch, areset circuit and a trip circuit, the mode switch adapted toelectrically connect the reset circuit to the motor means in oneposition and the trip circuit to the motor means in the other position,alternate movement of the first contact assembly means between thecontact reset engaged position and the contacts disengaged trippedposition causing the mode switch to move from one position to the other.2. A circuit control system according to claim 1 further including anindicator control switch disposed remotely from the load contactassemblies, the indicator control switch comprising a current responsivethermal element adapted to open and close a line coupling the electricalcircuit means to ground.
 3. A circuit control system according to claim1 further including current overload means operatively connected to themeans for latching and adapted to unlatch the load contact assembliesupon occurrence of a selected current overload.
 4. A circuit controlsystem according to claim 2 further including additional circuit meansarranged to direct sufficient current through the indicator controlswitch to cause it to open the line between the electrical circuit meansand ground.
 5. A circuit control system according to claim 4 in whichthe additional circuit means includes an on-off overload trip switch,the first contact assembly means adapted to place the overload tripswitch coupled to the line between the electrical circuit means andground in the off position when the first and second load contacts arein the reset engaged position and in the on position when the first andsecond load contacts are in the tripped disengaged position.
 6. Acircuit control system according to claim 1 in which the electricalcircuit means includes an interface circuit adapted to receive both mainand back up power supplies of both alternating and direct current.
 7. Acircuit control system according to claim 5 in which the additionalcircuit means includes first and second position temperature coefficient(PTC) elements and means are provided to place one PTC element incircuit relation with the indicator control switch when the controlsystem is supplied by alternating current and to place both PTC elementsin parallel circuit relation with each other and in circuit relationwith the indicator circuit switch when the control system is supplied bydirect current.
 8. A circuit control system according to claim 2 inwhich the indicator control switch is optically coupled to theelectrical circuit means.